JP6014647B2 - Electrical connector and electrical connection system - Google Patents

Description

  The present invention relates to an electrical connector, an electrical connection system, a lithographic apparatus, and a method for manufacturing a device.

  A lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually onto a target portion of the substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In that case, a patterning device, also referred to as a mask or a reticle, may be used to generate a circuit pattern formed on an individual layer of the IC. This pattern can be transferred onto a target portion (eg including part of, one, or more dies) on a substrate (eg a silicon wafer). Usually, the pattern is transferred by imaging on a radiation-sensitive material (resist) layer provided on the substrate. In general, a single substrate will contain a network of adjacent target portions that are successively patterned. Known lithographic apparatus include so-called steppers that irradiate each target portion by exposing the entire pattern onto the target portion at once, and simultaneously scanning the pattern in a certain direction (“scan” direction) with a radiation beam, A so-called scanner is included that irradiates each target portion by scanning the substrate parallel or anti-parallel to this direction. It is also possible to transfer the pattern from the patterning device to the substrate by imprinting the pattern onto the substrate.

  [0003] Some moving parts of the lithographic apparatus are powered by a high voltage power source. Furthermore, for some lithographic processes, part of the lithographic apparatus is maintained at a very low pressure. In particular, at very low pressures, an actuator used to position a table on which the substrate is placed, a so-called blade that blocks part of the projection beam, or a mask or substrate relative to a table that can be part of a lithographic apparatus A high voltage power supply may be used to power the clamp that holds The use of high voltages also has the problem that electrical breakdown can occur, especially because the components are placed in a very low pressure environment. The potential for electrical breakdown limits the voltage on the power line and presents a safety issue. When electrical breakdown occurs, it contaminates the surface of the optical component, creates electromagnetic interference that interferes with precision electronic components, and is harmful to humans.

  [0004] European Patent No. 1056162 (B1) discloses a device for controlling an electric field. This device utilizes a capacitive field controller and a geometric field controller. The capacitive electric field control unit includes a plurality of capacitive layers disposed substantially concentrically between the inner conducting conductor and the outer ground potential. The geometric electric field control unit includes a stress cone arranged at an electrical contact ground potential. However, arcing can still occur from the cable to nearby conductors. This type of arcing is particularly problematic when electrical cables are connected to systems that are at low pressure. In extreme ultraviolet (EUV) lithography, the lithographic process is performed at a very low pressure to reduce the absorption of EUV radiation by air.

  [0005] To solve this problem, US Pat. No. 6,485,331 (B1) discloses a connection system for electrical cables that operate under vacuum and carry high voltage electrical pulses or currents. Yes. This connection system includes a metal sheath of the cable and a grounded outer metal shell connected to the dielectric insulating sleeve. An insulating sheath and sleeve surround the cable to be connected. The system is fitted with a seal so as to form a sealed cavity between the insulating sleeve of the cable and the insulating sheath. This ensures that the insulator of the connection system is immersed in the gas atmosphere even if a part of the connection system is in a vacuum. This is intended to reduce arcing along the surface of the joint of the connection system insulator. However, it is difficult to prevent leakage in such a system. Any leakage in the system increases the potential for arcing.

  [0006] It would be desirable to provide an electrical connector that is suitable for connecting high voltage electrical cables at low pressures and that reduces or eliminates arcing.

  [0007] In one aspect of the present invention, an electrical connector is provided that includes a housing having a conductive surface and a plurality of cable inserts. Each cable insert includes an electrical conductor configured to connect to the electrical cable and an insulating sleeve surrounding the electrical conductor. The housing surrounds the plurality of cable insertion portions.

  [0008] In a further aspect of the present invention, an electrical connection system is provided that includes a male electrical connector and a female electrical connector. The male and female electrical connectors each include a housing having a conductive surface and a plurality of cable inserts. Each cable insert includes an electrical conductor configured to connect to the electrical cable and an insulating sleeve surrounding the electrical conductor. The housing surrounds the plurality of cable insertion portions. The male electrical connector and the female electrical connector are interconnected.

  [0009] In a further aspect of the invention, an electrical connection system is provided that includes an insulating sleeve and a plurality of conductive bands surrounding the insulating sleeve. There is a gap between each conductive band so that the insulating sleeve is exposed in each gap.

  [0010] Further, the present invention relates to lithography systems and subsystems that include connectors or connection systems.

[0011] Embodiments of various aspects of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings, in which: In the figure, corresponding reference symbols indicate corresponding parts.
FIG. 1 depicts a lithographic apparatus according to one embodiment of the invention. FIG. 2 shows a male / female pair of electrical connectors according to one embodiment of the present invention. [0014] FIG. 3 shows a theoretical Paschen curve of parallel plates in air. [0015] FIG. 4 illustrates an electrical connection system according to an embodiment of the present invention. [0016] FIG. 5 illustrates a beam interceptor connected to a power source by a connection system according to one embodiment of the present invention. [0017] FIG. 6 illustrates an electrostatic clamp connected to a power source by a connection system according to one embodiment of the present invention.

[0018] Figure 1 schematically depicts a lithographic apparatus according to one embodiment of the invention. The lithographic apparatus
[0019] an illumination system (illuminator) IL configured to condition a radiation beam B (eg, UV radiation or EUV radiation);
[0020] A support structure (eg, a mask table) configured to support the patterning device (eg, mask) MA and connected to a first positioner PM configured to accurately position the patterning device according to certain parameters MT)
[0021] A substrate table (eg, a wafer table) configured to hold a substrate (eg, resist-coated wafer) W and connected to a second positioner PW configured to accurately position the substrate according to specific parameters ) WT,
[0022] A projection system (eg, a refractive projection lens system) configured to project a pattern imparted to the radiation beam B by the patterning device MA onto a target portion C (eg, including one or more dies) of the substrate W. Including PS.

  [0023] The illumination system may be a refractive, reflective, magnetic, electromagnetic, electrostatic, or other type of optical component, or any of them, to induce, shape, or control radiation Various types of optical components such as combinations can be included.

  [0024] The support structure supports the patterning device, ie, bears the weight of the patterning device. The support structure holds the patterning device in a manner that depends on the orientation of the patterning device, the design of the lithographic apparatus, and other conditions, such as whether or not the patterning device is held in a vacuum environment. The support structure can hold the patterning device using mechanical, electrostatic or other clamping techniques. The support structure may be, for example, a frame or table that can be fixed or movable as required. The support structure may ensure that the patterning device is at a desired position, for example with respect to the projection system. Any use of the terms “reticle” or “mask” herein may be considered synonymous with the more general term “patterning device.”

  [0025] The term "patterning device" as used herein broadly refers to any device that can be used to provide a pattern in a cross section of a radiation beam so as to create a pattern in a target portion of a substrate. Should be interpreted. It should be noted that the pattern imparted to the radiation beam may not exactly match the desired pattern in the target portion of the substrate, for example if the pattern includes phase shift features or so-called assist features. Typically, the pattern imparted to the radiation beam may correspond to a particular functional layer in a device being created in the target portion, such as an integrated circuit.

  [0026] The patterning device may be transmissive or reflective. Examples of patterning devices include masks, programmable mirror arrays, and programmable LCD panels. Masks are well known in lithography, and include mask types such as binary, alternating phase shift, and attenuated phase shift, as well as various hybrid mask types. In one example of a programmable mirror array, a matrix array of small mirrors is used, and each small mirror can be individually tilted to reflect the incoming radiation beam in various directions. The tilted mirror imparts a pattern to the radiation beam reflected by the mirror matrix.

  [0027] As used herein, the term "projection system" refers to refractive, reflective, reflective, as appropriate to the exposure radiation used or to other factors such as the use of immersion liquid or the use of vacuum. It should be construed broadly to encompass any type of projection system including refractive, magnetic, electromagnetic, and electrostatic optical systems, or any combination thereof. Any use of the term “projection lens” herein may be considered as synonymous with the more general term “projection system”.

  [0028] As shown herein, the lithographic apparatus is of a reflective type (eg employing a reflective mask). Alternatively, the lithographic apparatus may be of a transmissive type (eg employing a transmissive mask).

  [0029] The lithographic apparatus may be of a type having two (dual stage) or more substrate tables (and / or two or more mask tables). In such "multi-stage" machines, additional tables can be used in parallel, i.e. one or more tables are used for exposure while a preliminary process is performed on one or more tables. You can also.

  [0030] Further, the lithographic apparatus is of a type capable of covering at least a part of the substrate with a liquid having a relatively high refractive index, for example water, so as to fill a space between the projection system and the substrate. May be. An immersion liquid may also be added to another space in the lithographic apparatus, for example, between the mask and the projection system. Immersion techniques are well known in the art for increasing the numerical aperture of projection systems. As used herein, the term “immersion” does not mean that a structure, such as a substrate, must be submerged in the liquid, but simply the liquid between the projection system and the substrate during exposure. It means that there is.

  [0031] Referring to FIG. 1, the illuminator IL receives a radiation beam from a radiation source SO. For example, if the radiation source is an excimer laser, the radiation source and the lithographic apparatus may be separate components. In that case, the radiation source is not considered to form part of the lithographic apparatus, and the radiation beam is directed from the radiation source SO to the illuminator IL, for example a beam delivery including a suitable guide mirror and / or beam expander. Sent using system BD. In other cases the source may be an integral part of the lithographic apparatus, for example when the source is a mercury lamp. The radiation source SO and the illuminator IL may be referred to as a radiation system, together with a beam delivery system BD if necessary.

  [0032] The illuminator IL may include an adjuster AD for adjusting the angular intensity distribution of the radiation beam. In general, at least the outer and / or inner radial extent (commonly referred to as σ-outer and σ-inner, respectively) of the intensity distribution in the illuminator pupil plane can be adjusted. In addition, the illuminator IL may include various other components such as an integrator IN and a capacitor CO. By adjusting the radiation beam using an illuminator, the desired uniformity and intensity distribution can be provided in the cross section of the radiation beam.

  [0033] A masking device may be included in the illuminator IL that defines a region on the patterned means to be illuminated. The masking device comprises a plurality of blades, for example four, whose positions can be controlled by actuators, for example stepper motors, whereby the beam cross-section can be defined. It should be noted that the masking device need not be positioned in proximity to the patterning means, but is generally in the plane imaged on the patterning means (the conjugate plane of the patterning means). The open area of the masking means defines an area on the irradiated patterning means, but may not be exactly the same if the intervening optical component has a magnification other than 1, for example.

  [0034] In one embodiment of the present invention, the masking device includes a beam interceptor 210 that includes opaque blades 211, 212, 213, 214 arranged to block a portion of the radiation beam B, as shown in FIG. including. These blades 211, 212, 213, 214 manipulate the size and shape of the projection beam B exposed on the mask MA and thus on the target portion C. The movement and positioning of the blades 211, 212, 213, 214 are controlled by the control system 220. If the target portion C to be projected is not fully positioned on the substrate W, the control system 220 is configured to determine a new size for this particular target portion C and activate the interceptor 210 accordingly.

  [0035] The patterning device (eg, mask MA) is held on the support structure (eg, mask table MT) and is patterned by the patterning device. The mask MA can be clamped on both sides of the mask with respect to the mask table MT. By clamping the mask MA on both sides, the mask can be subjected to large accelerations without slipping or deforming. Clamping or holding force may be applied using a thin film, which further prevents mask deformation. The clamp generates a normal force between the adjacent surfaces of the mask and the mask table MT, and as a result, friction occurs between the contact surfaces of the mask and the mask table. The clamping force on the face of the mask MA can be generated using electrostatic or mechanical clamping techniques.

  [0036] In an EUV lithography process, an electrostatic clamp may be used to clamp the mask MA to the mask table MT and / or the substrate W to the substrate table WT. FIG. 6 illustrates an exemplary electrostatic clamp connected to a power source 34 via an electrical connection system 21 according to one embodiment of the present invention. In the exemplary electrostatic clamp shown in FIG. 6, the chuck 60 includes a dielectric or slightly conductive body 61 having an embedded electrode 62. The power source 34 is used to apply a potential difference between the mask MA or the substrate W and the chuck 60 and between the chuck 60 and the tables MT and WT, and thereby the electrostatic force causes the mask MA or the substrate W and the chuck. 60 is clamped against the tables MT, WT. The embedded electrode 62 is connected to the power source 34.

  [0037] The radiation beam B is incident on the patterning device (eg, mask MA). After traversing the mask MA, the radiation beam B passes through the projection system PS, which focuses the beam onto the target portion C of the substrate W. Using the second positioner PW and the position sensor IF2 (eg, an interferometer device, linear encoder, or capacitive sensor), for example, the substrate table WT to position the various target portions C in the path of the radiation beam B. Can be moved accurately. Similarly, the first positioner PM and another position sensor IF1 can be used to accurately position the mask MA with respect to the path of the radiation beam B, for example after mechanical removal from the mask library or during a scan. it can. Usually, the movement of the mask table MT can be realized by using a long stroke module (coarse positioning) and a short stroke module (fine positioning) that form a part of the first positioning device PM. Similarly, movement of the substrate table WT can also be realized using a long stroke module and a short stroke module that form part of the second positioner PW. In the case of a stepper (as opposed to a scanner) the mask table MT may be connected only to a short stroke actuator or may be fixed. Mask MA and substrate W may be aligned using mask alignment marks M1, M2 and substrate alignment marks P1, P2. In the illustration, the substrate alignment mark occupies a dedicated target portion, but the substrate alignment mark can also be placed in the space between the target portion (these are known as scribe line alignment marks). Similarly, if multiple dies are provided on the patterning device (eg mask) MA, patterning device alignment marks may be placed between the dies.

  [0038] The example apparatus can be used in at least one of the modes described below.

  [0039] In step mode, the entire pattern applied to the radiation beam is projected onto the target portion C at once (ie, a single static exposure) while the mask table MT and substrate table WT remain essentially stationary. The substrate table WT is then moved in the X and / or Y direction so that another target portion C can be exposed. In step mode, the maximum size of the exposure field limits the size of the target portion C imaged during a single static exposure.

  [0040] 2. In scan mode, the mask table MT and substrate table WT are scanned synchronously while a pattern imparted to the radiation beam is projected onto a target portion C (ie, a single dynamic exposure). The speed and direction of the substrate table WT relative to the mask table MT can be determined by the (reduction) magnification factor and image reversal characteristics of the projection system PS. In the scan mode, the maximum size of the exposure field limits the width of the target portion during single dynamic exposure (non-scan direction), while the length of the scan operation determines the height of the target portion (scan direction). .

  [0041] 3. In another mode, while holding the programmable patterning device, the mask table MT remains essentially stationary and the substrate table WT is moved or scanned while the pattern applied to the radiation beam is moved to the target portion. Project onto C. In this mode, a pulsed radiation source is typically employed, and the programmable patterning device is further adapted as needed after each movement of the substrate table WT or between successive radiation pulses during a scan. Updated. This mode of operation can be readily applied to maskless lithography that utilizes programmable patterning device, such as a programmable mirror array of a type as described above.

  [0042] Combinations and / or variations on the above described modes of use or entirely different modes of use may also be employed.

  [0043] The first positioner PM, the second positioner PW, a motor that controls any blade that may be included in the masking device, and any clamp that may be included in the lithographic projection apparatus are powered by a high voltage power supply Is done. High voltage is taken to mean that the power supply produces an output on the order of hundreds or thousands of volts. In one embodiment, the power supply output is greater than 100V, greater than 200V, greater than 500V, greater than 1000V, greater than 2000V, and greater than 5000V.

  [0044] FIG. 2 schematically illustrates an electrical connection system 21 according to an embodiment of the present invention. This electrical connection system is a plug and socket connector including a male electrical connector 22 and a female electrical connector 23. The male and female connectors have complementary structures so that they are securely interconnected with each other. This forms an electrical connection between one or more pairs of electrical cables 24. For each pair of electrical cables 24 to be connected, one cable is electrically connected to the male connector 22 and one cable is electrically connected to the female connector 23.

  [0045] As described above, male and female connectors have different physical structures in several respects, but both types of connectors are embodiments of the present invention.

  An electrical connector (male or female) according to an embodiment of the invention includes a housing 25. The housing 25 can be made of a conductive material. Optionally, the housing material is a light alloy. Alternatively, the housing 25 can be made of an electrically insulating material, but has a conductive surface. For example, the housing 25 may be made of plastic and plated with a conductive material. The housing 25 may be die cast. The housing 25 is desirably corrosion resistant.

  In the exemplary embodiment shown in FIG. 2, the end of the housing 25 of the female connector 23 is configured to fit within the corresponding end of the housing 25 of the male connector 22. This helps to maintain each part in the correct relative position and helps to form a stable electrical connection between the pair of electrical cables 24.

  [0048] The housing 25 is intended to control the electric field generated by the electrical cable 24 connected to the electrical connector. For many lithographic applications, the voltage of the electrical cable is very high, for example hundreds or thousands of volts. Unless the electric field is controlled, suppressed or interrupted, there is a risk of arcing from the high voltage electrical cable 24 to another component of the lithographic apparatus.

  [0049] The housing 25 allows electrons in the dangerous direction to be captured by capturing free electrons from the electrical cable 24 before they obtain a dangerous level of kinetic energy and / or through gas in the environment of the connector. Controls the electric field by preventing it from being accelerated. Therefore, it is desirable that the conductive housing 25 be electrically connected to the ground potential. Thus, optionally, the housing 25 has a connection region on its outer surface configured to connect to ground potential.

  [0050] Accordingly, the housing 25 according to an embodiment of the present invention performs a function different from that of a conventional electrical connector housing. For example, some conventional electrical connectors have a housing made of an insulating material such as an insulating plastic. This provides mechanical protection to the connector. Such connectors may be suitable for use at low voltages, but in applications that require high voltage cables to be connected, they may not work due to arcing from the cable to another conductive component There is.

  [0051] In a standard electrical connector for connecting a coaxial cable, the outer housing of the connector completely surrounds the inner conductor of the coaxial cable when the outer conductor of the coaxial cable does not surround the inner conductor at the connection point. It is necessary to form a grounded screen. This aims to confine the electric field in the space between the inner conductor and the housing. The only break in the housing can be a sufficiently small vent so as not to significantly disturb the electric field.

  [0052] An electrical connector according to an embodiment of the present invention operates on different principles, and the housing does not need to form an uninterrupted grounded screen around the electrical cable. The housing 25 need only surround the cable insert 26 of the connector in which the cables and conductors carrying the voltage are located.

  [0053] As described above, the female and male connectors have complementary shapes so that they are firmly secured to each other. As an additional means of ensuring connection, a locking system may be provided on the connector housing. Such a locking system may take the form of two levers on either side of one housing of the male and female connectors. Two pairs of protruding pins are positioned on corresponding ends of the housing of the other connector. When the connector is connected, the lever stays hooked on the pin, thereby forming a secure connection. Alternatively, there may be only one lever and a pair of pins. Such a lever can be made, for example, from stainless steel. Alternatively or additionally, the locking system may include a screw and bolt system.

  [0054] The connector includes at least two cable inserts 26. Each cable insert 26 includes an electrical conductor 27 surrounded by an electrically insulating sleeve 28. The conductor 27 is configured to be connected to the end of the electric cable 24.

  [0055] Some manufacturing methods that utilize lithography need to be performed at very low pressures, such as 10 Pa. For example, a lithographic method using EUV radiation must be performed in a deep vacuum. This is because air absorbs EUV radiation. Therefore, each component of the lithographic apparatus must be suitable for use at low pressures. This also includes electrical connectors that connect one or more components of the lithographic apparatus to a high voltage power source. Furthermore, it is desirable that the same electrical connector can be used at atmospheric pressure.

  [0056] Suitable insulating materials for electrical connectors include liquid crystal polymers, polyetheretherketone (PEEK) or polytetrafluoroethylene (PTFE). Other insulators may also be suitable.

  [0057] The insulating sleeve 28 of the cable insertion portion 26 may take a substantially tube shape. The insulating sleeve 28 is disposed so as to substantially surround the end of the electric cable 24 to be connected. The end of the cable 24 is inserted into the cable insert 26, with the insulating sleeve of the cable itself removed, so that the insulating sleeve 28 of the electrical connector surrounds the end. Optionally, the inner surface of the insulating sleeve 28 can take the shape of a cylinder.

  [0058] The exact structure of the insulating sleeve 28 is desirably different between the male connector 22 and the female connector 23. In the exemplary embodiment shown in FIG. 2, the insulating sleeve 28 of the female connector 23 extends beyond the housing 25, while the insulating sleeve 28 of the male connector 22 terminates within the housing 25. . In one embodiment, the end of the insulating sleeve 28 of the female connector 23 closest to the male connector 22 fits within the end of the insulating sleeve 28 of the male connector 22 closest to the female connector 23. This helps to form a stable electrical connection by ensuring that the relative positions of the male and female connectors are stable.

  As shown in FIG. 2, a ridge 29 on the inner surface of the housing 25 may optionally be present with a corresponding flange 30 on the outer surface of the insulating sleeve 28. The flange 30 contacts the ridge 29. This helps to prevent the insulating sleeve 28 from sliding within the housing 25.

  [0060] Optionally, the end of each insulative sleeve 28 closest to the electrical cable 24 fits complementarily within the cover cap 31. The cover cap 31 surrounds the end of the insulating sleeve 28 and contacts the inner surface of the housing 25. The cover cap 31 is made of an insulating material such as liquid crystal polymer, polyetheretherketone (PEEK), or polytetrafluoroethylene (PTFE).

  [0061] The electrical conductor 27 of each cable insertion portion 26 determines whether the electrical connector is male or female. The conductor 27 of the male connector 22 fits into the conductor 27 of the female connector 23 and is in electrical contact with the conductor 27. Optionally, the male / female connector conductor 27 does not protrude beyond the connector housing 25.

  [0062] For both male and female connectors, the conductor 27 is configured to contact the electrical cable 24 to be connected. The electrical cable 24 is inserted into the rear end of the conductor 27, ie, the end of the conductor 27 furthest from the corresponding connector of the opposite type.

  A connection point between the electric cable 24 and the conductor 27 of the cable insertion portion 26 is called a terminal. This connection may be achieved by screw terminals. In the screw terminal, the end of the electric cable is held in a state of being in electrical contact with the conductor 27 using a screw electrically connected to the conductor 27. Alternatively, the terminal may be a crimp connection. In this case, the removed end of the electric cable 24 is inserted into the cable insertion portion 26. The part of the terminal is then tightly compressed around the cable by pressing the part of the terminal with a special crimping tool. As a further alternative, a cage-clamp terminal may be used.

  [0064] Under many circumstances, it is well known that the potential difference required for discharge between two electrical conductors increases with increasing pressure. For this reason, in the prior art, electrical connectors intended for use at low pressures have been configured to be airtight. In this case, the interior of the electrical connector can be maintained at a pressure higher than the ambient pressure. This prevents the breakdown voltage from decreasing with decreasing pressure, thereby reducing the possibility of arcing.

  [0065] However, it is very difficult to create an electrical connection system for connecting a pair of wires that is completely airtight. Any leakage in the connection system that is internally maintained at a pressure higher than ambient pressure will reduce the pressure in the connection system, thereby reducing the breakdown voltage and increasing the likelihood of arcing. End up.

  [0066] Alternatively, there may be a connection system in which the interior is maintained at a pressure lower than ambient pressure to increase the electrical breakdown voltage within the connection system. Any leakage in such a connection system increases the pressure in the connection system, thereby reducing the breakdown voltage and increasing the likelihood of arcing.

  [0067] For example, in a plug-and-socket electrical connector, a gas leak may occur at the overlap of the housings of the male and female connectors. Gas leakage is very difficult to prevent even where the electrical cable enters the back of the connector. The cable may not be airtight with the connector housing. This allows gas to pass through the space between the outer surface of the electrical cable and the housing of the connector.

  [0068] The electrical connector and electrical connection system according to one embodiment of the present invention need not be airtight. This is because the conductive housing controls the electric field as described above.

  [0069] In an electrical connector used to connect multiple pairs of cables, one electrical cable in addition to the risk of arcing between one of the electrical cables and another electrical component of the lithographic apparatus And the risk of arcing between adjacent electrical cables in the connection system. In the past, such cables had to be separated, for example, by a sufficient distance or separately by individual connection systems.

  [0070] In the electrical connector and electrical connection system of the present invention, the upper limit of the gap distance between conductors at various voltages is set. The upper limit depends on the pressure at which the connector or connection system is used.

  [0071] For an operating pressure of 10 Pa for an electrical connection system configured to connect an electrical cable carrying a voltage of 300 V, the maximum gap distance between the electrical conductors is preferably set to 80 mm. That is, in order to reduce the possibility of arcing between electrical cables in the connection system, the distance between any electrical cables in the connection system must be 80 mm or less.

The electrical cable 24 is in the insulating sleeve 28 of the cable insertion portion 26. Therefore, in order to achieve the maximum gap distance described above, the distance between the inner surfaces of any two insulating sleeves 28 of the electrical connector is set at d < 80 mm at a pressure of 10 Pa.

[0073] Optionally, as an additional safety measure, the gap distance in the electrical connection system is set to be five times smaller than the aforementioned maximum gap distance. The factor of 5 is d < 15 mm.

  [0074] The safety factor can be particularly important because the geometry of the electrical contacts affects the breakdown voltage. In the electrical connector according to one embodiment of the present invention, the conductor 27 in the insulating sleeve 28 has a pointed shape. This reduces the breakdown voltage, for example for parallel plates.

  [0075] For lithographic processes, it may be attempted to maintain the ambient pressure at 10 Pa, but there may be unintentional leakage of the vacuum vessel leading to increased pressure. At such low pressures, an increase in pressure can lead to a potentially dangerous decrease in breakdown voltage.

[0076] Optionally, the electrical connector is designed such that d < 40 mm. This is an appropriate upper limit for d when the connector is to be used at a pressure of 20 Pa. Optionally, using a 5 times safety factor, d < 8 mm.

  [0077] Optionally, the lithographic apparatus includes display means for displaying a signal indicating that the situation is safe when the pressure is 10 Pa or less. A pressure sensor detects the pressure in the vacuum vessel. When the pressure sensor detects that the pressure has increased above 10 Pa, no signal is displayed. Optionally, the lithographic apparatus has a safety device that prevents the pressure in the vacuum vessel from increasing above 20 Pa if there is an unintended leak.

  [0078] Optionally, the lithographic apparatus includes a safety shut-off system that switches off the power when the pressure increases above a certain pressure. For example, a pressure sensor detects the pressure. When it is detected that the pressure is higher than 20 Pa, for example, a signal is transmitted to the power source and the switch is turned off.

にしたがって圧力に反比例する。ここで、圧力ｐはパスカルで表され、間隙距離ｄはメートルで表される。任意選択的に、最大間隙距離は、１５０ｍｍ未満、８０ｍｍ未満、４０ｍｍ未満、３０ｍｍ未満、１５ｍｍ未満、８ｍｍ未満に設定される。 [0079] Generally, the maximum gap distance to be set is

Is inversely proportional to pressure. Here, the pressure p is expressed in Pascal, and the gap distance d is expressed in meters. Optionally, the maximum gap distance is set to less than 150 mm, less than 80 mm, less than 40 mm, less than 30 mm, less than 15 mm, and less than 8 mm.

  [0080] If the voltage carried by the electrical cable 24 connected by the connection system is known, an additional limit may be imposed on the maximum gap distance. Alternatively, if the connector is desired to be safe for use with electrical cables that carry voltages up to a certain limit, additional limits can be imposed on the maximum gap distance.

[0081] If it is desired that the connector be used for a voltage of up to 5 kV at a pressure of 10 Pa, the maximum gap distance is set as d < 30 mm, or set as d < 6 mm using a 5 times safety factor. Is done. For voltages up to 2 kV, the maximum gap distance is set as d < 30 mm, or d < 6 mm with a 5 times safety factor. Optionally, the maximum gap distance is set to less than 40 mm, less than 35 mm, less than 30 mm, less than 25 mm, less than 20 mm, less than 15 mm, less than 10 mm, less than 8 mm, and less than 7 mm.

となるように設定されうる。ここで、Ｖは、電気導体間の電位差である。この式は、導体間の理論上の電気的破壊電圧を予測するのに有用でありうる。しかし、実際の電気的破壊電圧は、この式から求められる値とは異なりうる。特に、破壊電圧は、電極の形状に依存して変化しうる。所与の状況における実際の電気的破壊電圧は、実験的に求められうる。 [0082] Generally, the maximum gap distance is

Can be set to be Here, V is a potential difference between electrical conductors. This equation can be useful in predicting the theoretical electrical breakdown voltage between conductors. However, the actual electrical breakdown voltage may be different from the value obtained from this equation. In particular, the breakdown voltage can vary depending on the shape of the electrode. The actual electrical breakdown voltage in a given situation can be determined experimentally.

  [0083] With the maximum distance between cables in an electrical connector set such that arcing is impossible or at least greatly reduced, each cable insert 26 needs to be surrounded by a separate housing There is no. The housing 25 need only surround the cable insert 26 when brought together to control the electric field.

  [0084] It is desirable that any region between the cable insertion portions 26 be occupied only by the electrically insulating material. That is, the housing 25 does not enter between the cable insertion portions 26 so as to isolate the cable insertion portions 26 from each other.

  [0085] In addition to the possibility of arcing between the electrical cables 24, there may be arcing from the electrical cable to the housing 25 of the connector. Thus, one of the above-mentioned maximum values of d is optionally applied to the distance between the inner surface of any insulating sleeve 28 and the housing 25.

  [0086] By setting the upper limit of the gap distance at a very low pressure, electrical breakdown is prevented, because the relationship between the breakdown voltage and the gap distance is different at low pressure compared to atmospheric pressure. . Specifically, at atmospheric pressure, as the gap distance decreases, the breakdown voltage decreases accordingly. However, if the pressure is low enough, the breakdown voltage increases dramatically as the gap distance decreases below the threshold distance. FIG. 3 shows a graph format of the relationship between the gap distance and the breakdown voltage at a pressure of 10 Pa.

  [0087] Under sufficiently low pressure conditions, electrical breakdown is more likely to occur along long gaps between electrical conductors than short paths. This means that if the distance between the electrical conductors in the electrical connector is sufficiently small and the pressure is sufficiently low, the breakdown voltage is too high for electrical breakdown to occur.

による間隙距離と圧力との積に関する。 [0088] Actually, the theoretical breakdown voltage is given by

It relates to the product of the gap distance and pressure.

[0089] The values of constants A and B depend on the composition of the gas in which the conductor is contained and the material and shape of the conductor. For parallel plates in air, A≈450 VPa ⁻¹ m ⁻¹ and B≈1.5, where V is measured in volts, p is measured in pascals, and d is measured in meters. As mentioned above, this equation can be used to predict the theoretical electrical breakdown voltage between conductors, but the actual electrical breakdown voltage in a given situation is the value determined by this equation. Can be different.

において生じる。曲線におけるこの転換点（「屈曲部（elbow）」）の右側では、破壊電圧は周知の態様で挙動することが見られ、増加する間隙距離と圧力と共に増加する。この屈曲部の左側では、破壊電圧は、間隙距離または圧力のいずれかが下がるにつれて劇的に増加する。したがって、放電は、積ｐｄが屈曲部の左側に確実にあるようにすることによって、減少または回避される。 [0090] The minimum value of V is

Occurs in. To the right of this turning point (“elbow”) in the curve, the breakdown voltage is seen to behave in a known manner and increases with increasing gap distance and pressure. On the left side of this bend, the breakdown voltage increases dramatically as either the gap distance or the pressure decreases. Thus, discharge is reduced or avoided by ensuring that the product pd is on the left side of the bend.

  [0091] By setting the maximum value of the gap distance at a low pressure in the electrical connector, arc discharge at a short gap distance can be prevented. The electric field control performed by the housing 25 prevents arcing along longer gap distances. Therefore, arc discharge at any gap distance is prevented by the combination of the maximum gap distance and electric field control.

にしたがって対応して変化する。例えば５倍である追加の安全係数を間隙距離の上限に適用してもよい。 [0092] In the above description, embodiments of the present invention have mainly been described for use at a maximum pressure of 10 Pa, but the maximum pressure may be set to different values, for example 5 Pa, 15 Pa or 20 Pa. Depending on the maximum operating pressure value and the maximum voltage of the electrical connector, the connector dimensional requirements

Correspondingly changes. For example, an additional safety factor of 5 may be applied to the upper limit of the gap distance.

  [0093] In one embodiment, the number of cable insertion portions 26 in the electrical connector is three. However, this number may be 2, 4, 5, 6, 9, etc.

  [0094] Figure 4 illustrates one embodiment of the present invention. This is an electrical connection system for connecting a single pair of electrical cables 24. In this embodiment, the connection system includes an insulating sleeve 28. This insulating sleeve 28 is configured to surround a connection 32 between the two electrical cables 24 to be connected. Specifically, the insulating sleeve surrounds a portion of the electrical cable from which the insulating portion of the electrical cable itself has been removed. The insulating sleeve 28 is made of an insulating material such as liquid crystal polymer, polyetheretherketone (PEEK), or polytetrafluoroethylene (PTFE).

  [0095] Two conductive bands 33 surround the insulating sleeve. These bands 33 are on either side of the point 32 where the two electrical cables are connected. Although FIG. 4 shows two conductive bands, there may be a greater number of conductive bands 33, for example 3 or 4.

  The conductive band 33 is intended to control the electric field generated by the electric cable 24 to be connected. This prevents arcing from the electrical cable 24 to electrical components outside the connection. This arcing prevention method is effective even if a portion or portions of the insulating sleeve 28 surrounding the connection 32 are exposed (ie, not shielded by a conductor).

  [0097] In use, the conductive band 33 is connected to the ground potential. Therefore, the conductive band 33 preferably includes a connection region 34 configured to connect to ground potential.

  The electrical connection system may be formed as an interconnected combination of male and female electrical connectors, each having a conductive band 33 that surrounds the insulating sleeve 28. In this case, when the male and female connectors are joined together, the insulating sleeves are interconnected, but the conductive bands 33 are not in physical contact with each other.

  [0099] Further, the optional features of the various forms of conductor terminals and insulating cover caps are applicable to this connection system as well as the embodiments of the invention described above.

  [00100] The above-described embodiments of the electrical connector and electrical connection system 21 of the present invention are suitable for use in a lithographic apparatus for connecting a mask table or substrate table actuator to a power source 34. Furthermore, embodiments of the present invention may be used with any beam interceptor 210 (eg, a blade) or any clamp (eg, electrostatic clamp) used to secure a mask or substrate to a table that may form part of a lithographic apparatus. ) Can be used to connect. However, electrical connectors and electrical connection systems according to embodiments of the invention are not limited to use as part of a lithographic apparatus. Electrical connectors and electrical connection systems are also applicable in other situations where it is desirable to connect electrical cables carrying high voltages in a low pressure environment.

  [0100] Although specific reference is made herein to the use of a lithographic apparatus in IC manufacturing, the lithographic apparatus described herein is an integrated optical system, a guidance pattern and a detection pattern for a magnetic domain memory, It should be understood that other applications such as the manufacture of flat panel displays, liquid crystal displays (LCDs), thin film magnetic heads and the like may be had. As will be appreciated by those skilled in the art, in such other applications, the terms “wafer” or “die” as used herein are all more generic “substrate” or “target portion” respectively. May be considered synonymous with the term. The substrate described herein can be used, for example, before or after exposure, such as a track (usually a tool for applying a resist layer to the substrate and developing the exposed resist), a metrology tool, and / or an inspection tool. May be processed. Where applicable, the disclosure herein may be applied to substrate processing tools such as those described above and other substrate processing tools. Further, since the substrate may be processed multiple times, for example, to make a multi-layer IC, the term substrate as used herein may refer to a substrate that already contains multiple processing layers.

  [00101] Although specific reference has been made to the use of embodiments of the present invention in the context of optical lithography as described above, it will be appreciated that embodiments of the present invention may be used in other applications, such as imprint lithography. It is not limited to optical lithography if the situation permits, as well. In imprint lithography, the topography within the patterning device defines the pattern that is created on the substrate. The topography of the patterning device is pressed into a resist layer supplied to the substrate, whereupon the resist is cured by electromagnetic radiation, heat, pressure, or a combination thereof. The patterning device is moved out of the resist leaving a pattern in it after the resist is cured.

  [0102] As used herein, the terms "radiation" and "beam" refer to ultraviolet (UV) (eg, wavelengths of 365 nm, 355 nm, 248 nm, 193 nm, 157 nm, or 126 nm, or approximately the wavelength of these values). ), And extreme ultraviolet (EUV) (having a wavelength in the range of 5-20 nm), and all types of electromagnetic radiation, including particulate beams such as ion beams and electron beams.

  [0103] The term "lens" can refer to any one or combination of various types of optical components, including refractive, reflective, magnetic, electromagnetic, and electrostatic optical components, depending on the context.

  [0104] While specific embodiments of the invention have been described above, it will be appreciated that the invention may be practiced otherwise than as described. For example, the invention may be in the form of a computer program comprising a sequence of one or more machine-readable instructions representing the method disclosed above, or a data storage medium (eg, semiconductor memory, magnetic disk) on which such a computer program is stored. Or an optical disk).

  [0105] The descriptions above are intended to be illustrative, not limiting. Thus, it will be apparent to one skilled in the art that modifications may be made to the invention as described without departing from the scope of the claims set out below.

Claims (7)

A male or female electrical connector (22, 23),
A plurality of cable inserts having an electrical conductor (27) connected to the electrical cable (24) and an insulating sleeve (28) surrounding the electrical conductor; and a housing having a conductive surface and surrounding the plurality of cable inserts (25)
The interior of the electrical connector is fluidly connected to the exterior of the connector ,
An electrical connector wherein each region between the insulating sleeves is occupied only by an electrically insulating material . A male or female electrical connector (22, 23),
A plurality of cable inserts having an electrical conductor (27) connected to the electrical cable (24) and an insulating sleeve (28) surrounding the electrical conductor; and a housing having a conductive surface and surrounding the plurality of cable inserts (25)
The interior of the electrical connector is fluidly connected to the exterior of the connector,
Each cable insertion portion includes the insulating cover cap surrounding the end of the insulating sleeve (31), electrical connector. The electrical connector of claim 1 or 2 , wherein a maximum distance d between inner surfaces of the insulating sleeve is less than about 80 mm. The electrical connector of claim 3 , wherein a maximum distance d between inner surfaces of the insulating sleeve is less than about 30 mm. The electrical connector according to claim 3 or 4 , wherein a maximum distance d between each inner surface of the insulating sleeve and the housing is less than about 80 mm. The electrical connector of claim 5 , wherein a maximum distance d between each inner surface of the insulating sleeve and the housing is less than about 30 mm. Electrical connection system comprising a male electrical connector according to any one of claims 1 6 (22), a female electrical connector (23) according to any one of claims 1 to 6, the ( 21)
An electrical connection system in which the male electrical connector and the female electrical connector are interconnected.

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